With the highly increasing development in the electrical industries, the direction of the research and design for the electronic products has gradually shifted to multi-function and high performance. In order to satisfy the packaging requests of integration and miniaturization for the semiconductor packaging, the circuit board that carrying a plurality of the active, non-active components and the circuits has evolved to multi-layer board gradually.
The development of semiconductor technology improves day by day rapidly, besides mainly focusing on the tiny packaging of the model, nowadays the data storage capacity is increasing gradually also. Therefore, with the increasing data amount, the least time taken to process the same amount data shows a higher efficiency in data processing. The straightest way to increase the processing rate of processor is to increase the operating frequency, but facing bottlenecks such as heat dissipation for high power, delay of signal time and electric magnetic interruption (EMI) when the data transmission is above Gb/s, which makes the fabrication of the higher performance semiconductor more difficult. Especially when the copper circuit is conventionally used as a carrier for data transmission, with the natural conductivity limitation of this material, the achieved conductivity cannot be further increased, therefore the signal transmission rate cannot be increased by increasing the conductivity.
In addition, the metallic circuit structure for signal transmission is easy to have interruption form the outside noise or interference form the inner circuit, results in signal transmission error due to the interruption and interference during the signal transmission process; therefore, some protection methods are required for the signal transmission structure to prevent the interruption and interference occur to affect the signal, especially obvious in the high frequency transmission. The protection methods have increased some difficulties and extra structure design for the circuit design, results in increasing in the design cost and the fabrication cost, and therefore, the present condition is hard to make a breakthrough.
Moreover, the conventional signal transmission method is an analogue signal transmission method using electricity flowing through the conductor, but the signal processing methods inside the circuits nowadays mostly are digital processing; therefore a distortion may occur after conversion during the transmission process.
In order to resolve the drawbacks from the conventional analogue signal transmission structure, new technique of transmission method is using the optical signal to replace the electrical signal, and the most obvious improvement is that the optical signal almost will not be interrupted by the electric and magnetic wave; therefore has a better signal transmission quality and reduce the signal transmission distortion. Also the structure design for preventing electric and magnetic wave can be decreased, results in reducing the design and fabrication cost. Thus, using optics as a signal transmission method has become a direction in future development.
Referring to FIG. 1 for the U.S. Pat. No. 6,839,476, showing a saturated layer 12 forming above the bottom layer 11, and a plurality of grooves 12a are formed in the saturated layer 12; then place an optical fiber 13 into the groove 12a, and form another top layer 14 above the saturated layer 12 to embed the optical fiber 13 in the saturated layer 12; thereof the optical fiber 13 is a core 13a covered by a cladding 13b outside. Then the two terminals of the optical fiber 13 can be set up with optical emitter and receiver modules and optical passive components, to transmit optical signal by the optical fiber 13 to avoid the drawbacks from electrical signal transmission.
However, the optical fiber 13 is embedded in the saturated layer 12 and the groove 12a, thus the saturated layer 12 needs to have a grooving fabrication first, then places the optical fiber 13 into the groove 12a. An automatic placing movement, like the conventional insertion movement when inserting electronic components into circuit board, completes the fabrication process of placing the optical fiber 13 into the groove 12a; therefore the speed of the fabrication is slow, and cannot achieve the rapid production purpose.
Moreover, the optical fiber 13 needs to be cut first according to the corresponding groove 12a length, and then places the optical fiber 13 into the groove 12a, which adds another process in the fabrication, therefore increases the fabrication difficulty; and the optical fiber 13 has different lengths, thereof increases the fabrication assorting difficulties, leads to the addition of complexity of the whole fabrication process, and consequently increases the fabrication cost.
At forming the groove 12a on the saturated layer 12 to place the optical fiber 13, the gap between the groove 12a and another groove 12a needs to be relatively spaced in size design, in order to locate the optical fiber 13 into the saturated layer 12; the distance of the gap affects the optical transmission element (such as optical fiber or waveguide) layout density, also the optical transmission element layout density is affected by the size of diameter of the optical fiber 13, thus, cannot achieve the purpose of high density optical transmission element layout.
Beside, the optical fiber 13 used to transmit the optical signal is a core 13a covered by cladding 13b, and the inner layer of the cladding 13b can be used as reflection surface to allow the optical signal reflects forward continuously via the inner layer of the cladding 13b to achieve the signal transmission purpose. The optical fiber 13 and the circuit board have different fabrication structure, thus needs to be fabricated by another independent fabrication process and increases difficulty of the whole fabrication process; and to integrate the two different fabrication products increase difficulty as well, thus cannot achieve the mass production purpose to lower the fabrication cost.
Thus, the increasing fabrication difficulty and cost due to optical fiber 13 has to be embedded in the saturated layer 12, and further, failing to meet the high density optical transmission element layout requirements, has become problems for industries desired to be resolved.
Therefore, to provide an integrated device that can solve problems such as meet the small and lightweight electronic device requirement, lower the signal transmission loss, shorten the conduction path, reduce the noise, and thereby, leads to increase the optoelectronic signal transmission quality, simplify the fabrication process, reduce the fabrication difficulty, increase the optical transmission element layout density, and improve the structure of the mass production circuit board with optoelectronic component embedded therein is a problem desires to be solved in industries.